Design of infiltration and percolation facilities is similar to detention facilities. The storage volume of an infiltration basin being the ponding volume on top of the infiltration surface and the volume of a percolation facility being the pore volume inside the underground percolation pit. It has been observed that infiltration and percolation facilities work best for very small runoff basins such as individual lots. They have to be designed conservatively using low unit loading rates and need to rest between runoff events to let the pores in the receiving soils rejuvenate. When the loading rates are too high, pores tend to seal.